Just in case people didn't notice, that waveform is upside down. The zero line is the 2nd one, just under the top line. So there's a lot of DC current in this, around 0.95 amps, plus the added 0.1 amps triplen current, mostly 3x, but some higher harmonics like 9x are also present. That DC+triplen current would be approximately equivalent to 1.44 amps of AC. Given that 100 watts through 144 ohms is 0.833333 amps, we're seeing about 72% overcurrent on the neutral compared to plain 100 watt resistive load without a diode on just one phase alone ... even before we consider the saturation effects the DC will have on the supplying transformer.
These things might be OK when the amount of load they are part of is a very small percentage of the transformer and wiring ratings. But on a grand scale, it can be very unsafe. Just use a smaller wattage bulb or switch to CFL (or both).
I'm wondering if any cheap CFLs have DC and/or harmonic currents.
